Final answer:
The exclusion that protects the employer under the Employee Polygraph Protection Act (EPPA) in this case is that the federal contractor was involved in national security.
Step-by-step explanation:
The exclusion that protects the employer under the Employee Polygraph Protection Act (EPPA) in this case is option (c) The federal contractor was involved in national security.
The EPPA prohibits most private employers from using lie detector tests, including polygraph tests, for pre-employment screening or during the course of employment. However, there are exemptions to this rule. In terms of national security, the EPPA allows federal contractors who are involved in intelligence or counterintelligence functions to administer polygraph tests to certain employees.
In this scenario, since the employee is working in counterintelligence, which is related to national security, the federal contractor may be protected from liability under the EPPA if they required the employee to submit to a polygraph test.